TVS - Varistors, MOVs

Part Number	Description / PDF	Quantity
VC1210K401R020 KEMET	VARISTOR 33V 400A 1210	0
VA2220K122R017 KEMET	VARISTOR 27V 1.2KA 2220	0
VP3225K401R130 KEMET	VARISTOR 205V 400A 2SMD JLEAD	0
VE1812K801R025 KEMET	VARISTOR 39V 800A 1812	860
VE1206M151R006 KEMET	VARISTOR 11V 150A 1206	10
VE1210K401R017 KEMET	VARISTOR 27V 400A 1210	0
VA1210K401R020 KEMET	VARISTOR 33V 400A 1210	0
VE1206K121R040 KEMET	VARISTOR 68V 120A 1206	0
VE1812K601R035 KEMET	VARISTOR 56V 600A 1812	0
VE1812K801R020 KEMET	VARISTOR 33V 800A 1812	0
VE1206K121R050 KEMET	VARISTOR 82V 120A 1206	0
VC1206K121R035 KEMET	VARISTOR 56V 120A 1206	0
VA1812K801R040 KEMET	VARISTOR 68V 800A 1812	0
VE2220K102R035 KEMET	VARISTOR 56V 1KA 2220	884
VC2220L122R008 KEMET	VARISTOR 15V 1.2KA 2220	0
VC2220K122R020 KEMET	VARISTOR 33V 1.2KA 2220	0
VC1812K401R060 KEMET	VARISTOR 100V 400A 1812	5813
VC1210K401R014 KEMET	VARISTOR 22V 400A 1210	0
VE0805L121R008 KEMET	VARISTOR 15V 120A 0805	0
VC1210K401R011 KEMET	VARISTOR 33V 400A 1210	0

TVS - Varistors, MOVs

1. Overview

Transient Voltage Suppressors (TVS), Varistors, and Metal Oxide Varistors (MOVs) are critical components for protecting electronic circuits from voltage spikes and electrostatic discharge (ESD). These devices clamp excessive voltage to safe levels, preventing damage to sensitive components. TVS diodes are semiconductor-based solutions with fast response times, while Varistors (including MOVs) use nonlinear resistive materials to absorb energy. Their importance spans industries like telecommunications, automotive, and consumer electronics, ensuring reliability in environments exposed to electrical surges.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
TVS Diodes	Unidirectional/bidirectional clamping, sub-nanosecond response time, low leakage current	Communication interfaces (USB, HDMI), microcontrollers, power supplies
Zinc Oxide Varistors	High energy absorption, voltage-dependent resistance, aging characteristics	Power line protection, industrial motor drives, surge protection strips
MOVs	Specialized varistors with metal oxide ceramics, optimized for AC/DC applications	Appliances, LED lighting, renewable energy systems

3. Structure and Composition

TVS diodes employ a PN junction semiconductor structure with doping profiles optimized for breakdown characteristics. Varistors consist of polycrystalline ceramic materials (typically zinc oxide grains with additives) sandwiched between metal electrodes, encapsulated in epoxy or molded housings. MOVs use similar materials to varistors but with enhanced grain boundary engineering for improved voltage clamping. All devices incorporate termination coatings (e.g., silver, tin) for PCB mounting compatibility.

4. Key Technical Parameters

Parameter	Description	Importance
Clamping Voltage (V_CLAMP)	Voltage level during surge conduction	Determines protection level for downstream components
Response Time	Time to transition from blocking to clamping mode	TVS: 0.5-10 ns; MOVs: 10-50 ns
Energy Absorption (W_ADM)	Maximum surge energy handling capability	Measured in joules (J), critical for industrial applications
Leakage Current	Off-state current at rated voltage	Impacts power efficiency, typically <100 A

5. Application Fields

Key industries include:

Consumer Electronics: Smartphone charging circuits, TV power supplies
Industrial Automation: PLCs, motor drives, sensor interfaces
Automotive: ECU protection, CAN bus interfaces, battery management systems
Renewable Energy: Solar inverters, wind turbine controllers

Case Study: MOVs in smart meters provide 10kA surge protection against grid transients.

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Specifications
Littelfuse	SM712-02	12A, 13.3V clamping, bidirectional TVS for RS-485
Bourns	V14450A	14mm MOV, 450VAC, 210J energy rating
STMicroelectronics	TV05C060	0.5W, 6V, ultra-small TVS for IoT devices

7. Selection Guidelines

Key considerations:

Operating voltage vs. clamping voltage margin
Surge current requirements (8/20 s waveform standard)
Package size constraints (SMD vs. through-hole)
Environmental conditions (temperature, humidity)
Lifespan expectations (MOVs degrade with repeated surges)

8. Industry Trends

Emerging trends include:

Miniaturization: Sub-0201 TVS devices for mobile applications
Higher energy density: MOVs with >1000J/cm absorption
Integration: Combined ESD and surge protection solutions
Automotive focus: AEC-Q qualified devices for 48V systems
Green manufacturing: Lead-free and RoHS-compliant materials